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Sponge Filters
PPI Comparison
4.25" Replacement for Hydro (sponge only)
6" Replacement for Hydro (sponge only)
Hydro Foam Replacement
Hydro Sponge Filter
Old-time Sponge Filter Style
Replacement Sponge for old-time filters
Old-time Sponge Filter Style
Old-time Spong Filter Lift Tube

Filter - Replacement Foam

$4.25
Shipping calculated at checkout.

Made from our Pro-Level Reticulated Foam, specifically suited for colonizing nitrifying bacteria at the highest levels in your aquarium.

As you can see from the list below, a 4.25" cube contains a lot more foam than a 4" one - over 20% more!

  • 3" cube filter has a volume of 27 cubic inches
  • 3.25" cube filter has a volume of 34 cubic inches
  • 4" cube filter has a volume of 64 cubic inches
  • 4.25" cube filter has a volume of 77 cubic inches
  • 5" cube filter has a volume of 125 cubic inches

The Filter - Replacement Foam destined to impress, and priced at only $2.50.

Inventory Last Updated: Nov 29, 2025

Customer Reviews

Based on 7 reviews
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J
Jim Randall
Filter repair

Restored my filters perfectly

J
Jim

Fit my old filters perfectly

C
Carolyn Butler
Foam Filters!

These r a great product! We use these in all our 25 tanks and nothing else!
Maintenance is so simple, a few squeezes in some changed out tank water and ur good to go! Recommend them to anybody!

C
Carolyn

Love these filters

J
Jason Reiss
Great buy

Excellent product

12
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